Flip meaning of orientation in stem().

QuLogic · QuLogic · commit c022b2261e46 · 2020-08-12T23:43:43.000-04:00
diff --git a/doc/users/next_whats_new/stem_orientation.rst b/doc/users/next_whats_new/stem_orientation.rst
@@ -4,8 +4,8 @@ When creating stem plots, you can now pass in an *orientation* argument to
 `.Axes.stem` or `.pyplot.stem`.
 
 Currently, only ``'vertical'`` and ``'horizontal'`` orientations are supported,
-with ``'horizontal'`` being the default.
+with ``'vertical'`` being the default.
 
 Example
 ```````
-stem(x, x, orientation='vertical')
+stem(x, x, orientation='horizontal')
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -2723,14 +2723,14 @@ def broken_barh(self, xranges, yrange, **kwargs):
 
     @_preprocess_data()
     def stem(self, *args, linefmt=None, markerfmt=None, basefmt=None, bottom=0,
-             label=None, use_line_collection=True, orientation='horizontal'):
+             label=None, use_line_collection=True, orientation='vertical'):
         """
         Create a stem plot.
 
         A stem plot draws lines perpendicular to a baseline at each location
         *locs* from the baseline to *heads*, and places a marker there. For
-        horizontal stem plots (the default), the *locs* are *x* positions, and
-        the *heads* are *y* values. For vertical stem plots, the *locs* are
+        vertical stem plots (the default), the *locs* are *x* positions, and
+        the *heads* are *y* values. For horizontal stem plots, the *locs* are
         *y* positions, and the *heads* are *x* values.
 
         Call signature::
@@ -2743,12 +2743,12 @@ def stem(self, *args, linefmt=None, markerfmt=None, basefmt=None, bottom=0,
         Parameters
         ----------
         locs : array-like, default: (0, 1, ..., len(heads) - 1)
-            For horizontal stem plots, the x-positions of the stems.
-            For vertical stem plots, the y-positions of the stems.
+            For vertical stem plots, the x-positions of the stems.
+            For horizontal stem plots, the y-positions of the stems.
 
         heads : array-like
-            For horizontal stem plots, the y-values of the stem heads.
-            For vertical stem plots,  the x-values of the stem heads.
+            For vertical stem plots, the y-values of the stem heads.
+            For horizontal stem plots, the x-values of the stem heads.
 
         linefmt : str, optional
             A string defining the properties of the vertical lines. Usually,
@@ -2779,12 +2779,12 @@ def stem(self, *args, linefmt=None, markerfmt=None, basefmt=None, bottom=0,
         basefmt : str, default: 'C3-' ('C2-' in classic mode)
             A format string defining the properties of the baseline.
 
-        orientation : str, default: 'horizontal'
-            If 'vertical', will produce a vertically-oriented stem plot,
-            else it will produce a horizontally-oriented stem plot.
+        orientation : str, default: 'vertical'
+            If 'vertical', will produce a plot with stems oriented vertically,
+            otherwise the stems will be oriented horizontally.
 
         bottom : float, default: 0
-            The y-position of the baseline.
+            The y/x-position of the baseline (depending on orientation).
 
         label : str, default: None
             The label to use for the stems in legends.
@@ -2822,7 +2822,7 @@ def stem(self, *args, linefmt=None, markerfmt=None, basefmt=None, bottom=0,
         else:
             locs, heads, *args = args
 
-        if orientation == 'horizontal':
+        if orientation == 'vertical':
             self._process_unit_info(xdata=locs, ydata=heads)
             locs = self.convert_xunits(locs)
             heads = self.convert_yunits(heads)
@@ -2880,7 +2880,7 @@ def stem(self, *args, linefmt=None, markerfmt=None, basefmt=None, bottom=0,
 
         # New behaviour in 3.1 is to use a LineCollection for the stemlines
         if use_line_collection:
-            if orientation == 'vertical':
+            if orientation == 'horizontal':
                 stemlines = [
                     ((bottom, loc), (head, loc))
                     for loc, head in zip(locs, heads)]
@@ -2898,7 +2898,7 @@ def stem(self, *args, linefmt=None, markerfmt=None, basefmt=None, bottom=0,
         else:
             stemlines = []
             for loc, head in zip(locs, heads):
-                if orientation == 'vertical':
+                if orientation == 'horizontal':
                     xs = [bottom, head]
                     ys = [loc, loc]
                 else:
@@ -2909,7 +2909,7 @@ def stem(self, *args, linefmt=None, markerfmt=None, basefmt=None, bottom=0,
                                marker=linemarker, label="_nolegend_")
                 stemlines.append(l)
 
-        if orientation == 'vertical':
+        if orientation == 'horizontal':
             marker_x = heads
             marker_y = locs
             baseline_x = [bottom, bottom]
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
@@ -3018,8 +3018,8 @@ def stackplot(
 @_copy_docstring_and_deprecators(Axes.stem)
 def stem(
         *args, linefmt=None, markerfmt=None, basefmt=None, bottom=0,
-        label=None, use_line_collection=True,
-        orientation='horizontal', data=None):
+        label=None, use_line_collection=True, orientation='vertical',
+        data=None):
     return gca().stem(
         *args, linefmt=linefmt, markerfmt=markerfmt, basefmt=basefmt,
         bottom=bottom, label=label,
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -3289,7 +3289,7 @@ def test_stem_orientation(use_line_collection):
                   use_line_collection=use_line_collection)
 
     fig, ax = plt.subplots()
-    ax.stem(*args, **kwargs, orientation='vertical')
+    ax.stem(*args, **kwargs, orientation='horizontal')
 
 
 @image_comparison(['hist_stacked_stepfilled_alpha'])
